Make IP Allowlist available from Pro + Plan

[anthony-dgx]

What does this PR do?

IP Allowlist is now a feature available for customers on Infra Pro + and Infra Entreprise plans. I'm updating our documentation to reflect that update.

Additional Notes

Review checklist

Please check relevant items below:

• [ ] This PR includes all newly recorded cassettes for any modified tests.

• [ ] This PR does not rely on API client schema changes.

  • [ ] The CI should be fully passing.

• [ ] Or, this PR relies on API schema changes and this is a Draft PR to include tests for that new functionality.

  • Note: CI shouldn't be run on this Draft PR, as its expected to fail without the corresponding schema changes.